1ch uart w/ narrow parallell interface...?

Are there any uarts around with a "narrow" parallell interface which can 
be utilized from a uC w/o a full-blown address/data bus system? I am 
aware of the possibility of using SPI-type uarts - but for various 
reasons those are not an alternative this time.

I was thinking about the possibility of using 8-9-10 general IO lines on 
a uC and I guess I should use an interrupt line as well.

Small footprint, low pin count, smd (of course), low price?

Ideas, anyone?

-- 
Torbj�rn Heltne

Torbj�rn Heltne wrote:
> Are there any uarts around with a "narrow" parallell interface which
> can be utilized from a uC w/o a full-blown address/data bus system? I
> am aware of the possibility of using SPI-type uarts - but for various
> reasons those are not an alternative this time.
>
> I was thinking about the possibility of using 8-9-10 general IO lines
> on a uC and I guess I should use an interrupt line as well.
>
> Small footprint, low pin count, smd (of course), low price?
>
> Ideas, anyone?

It would be useful if you could add a little more detail to your 
requirements such as speed.

Depending on how busy your uC is, you could bit-bang the serial port if the 
data rate is not too high.  We have done this on projects where space and 
cost were at an absolute premium.

It was not clear why you can't use SPI, but if what you mean is you can't 
use SPI for the serial port, you might use a separate small micro that has 
both SPI and serial.  You talk to the SPI port from your micro and it talks 
to the serial port.

Scott 

Torbj�rn Heltne wrote:
> Are there any uarts around with a "narrow" parallell interface which can 
> be utilized from a uC w/o a full-blown address/data bus system? I am 
> aware of the possibility of using SPI-type uarts - but for various 
> reasons those are not an alternative this time.
> 
> I was thinking about the possibility of using 8-9-10 general IO lines on 
> a uC and I guess I should use an interrupt line as well.
> 
> Small footprint, low pin count, smd (of course), low price?
> 
> Ideas, anyone?
> 
Hi,

How about a micro with built-in serial. PIC16F628, or PIC16F870 both 
have uarts.

-- 
Luhan Monat: luhanis(at)yahoo(dot)com
http://members.cox.net/berniekm
"The Future is not what it used to be..."

> It would be useful if you could add a little more detail to your 
> requirements such as speed.
> 
> Depending on how busy your uC is, you could bit-bang the serial port 
> if the data rate is not too high.  We have done this on projects 
> where space and cost were at an absolute premium.
> 
> It was not clear why you can't use SPI, but if what you mean is you 
> can't use SPI for the serial port, you might use a separate small 
> micro that has both SPI and serial.  You talk to the SPI port from 
> your micro and it talks to the serial port.

Speed requirements are <= 38400, amount of data max 150cps in each 
direction. I have read some on a few bit-banged serial port 
implementations. Common for all of them were that they were half duplex 
only. I need full duplex. I guess it is absolutely possible to achieve 
that but I think I prefer a hardware solutiuon anyway.
I'm not too sure why I don't want to use the SPI-interface for asynch 
SCI communication. You're more than welcome to give me reasons to do it 
that way.


> How about a micro with built-in serial. PIC16F628, or PIC16F870 both 
> have uarts.

I'm already aiming for a micro with built in serial, the ATmega16. I 
need a second serial port.

-- 
Torbj&#4294967295;rn Heltne

"Torbj&#4294967295;rn Heltne" <torbjorn.heltne@amelektronikk.no> wrote in message
news:419dce17$1@news.broadpark.no...
>
> I'm already aiming for a micro with built in serial, the ATmega16. I
> need a second serial port.

Why not go for the ATmega162. It has two serial ports.

Meindert

Meindert Sprang wrote:

> Why not go for the ATmega162. It has two serial ports.

I can do without the TWI but need a couple of A/D channels.

-- 
Torbj�rn Heltne

Torbj�rn Heltne wrote:
>> It would be useful if you could add a little more detail to your 
>> requirements such as speed.
>>
>> Depending on how busy your uC is, you could bit-bang the serial port 
>> if the data rate is not too high.  We have done this on projects where 
>> space and cost were at an absolute premium.
>>
>> It was not clear why you can't use SPI, but if what you mean is you 
>> can't use SPI for the serial port, you might use a separate small 
>> micro that has both SPI and serial.  You talk to the SPI port from 
>> your micro and it talks to the serial port.
> 
> 
> Speed requirements are <= 38400, amount of data max 150cps in each 
> direction. I have read some on a few bit-banged serial port 
> implementations. Common for all of them were that they were half duplex 
> only. I need full duplex. I guess it is absolutely possible to achieve 
> that but I think I prefer a hardware solutiuon anyway.

The smallest Std UART with a narrow parallel BUS is the 2691 from 
Philips. Comes in 24 DIP and SO packages.


> I'm not too sure why I don't want to use the SPI-interface for asynch 
> SCI communication. You're more than welcome to give me reasons to do it 
> that way.

You may find that a small uC with SPI+UART, is cheaper/smaller than a 
small UART. Philips have tiny LPC91x series uC devices as small as 14 
pins, with UART and SPI ports, so you can add as many Duplex UARTS as 
you want....

-jg

Someone wrote:

>> Speed requirements are <= 38400, amount of data max 150cps in each 
>> direction. I have read some on a few bit-banged serial port 
>> implementations. Common for all of them were that they were half 
>> duplex only. I need full duplex. I guess it is absolutely possible to 
>> achieve that but I think I prefer a hardware solutiuon anyway.
> 

There are several simple UARTS available at opencores, and they should 
fit nicely into a couple of dollarsworth of PLD, say a Xilinx XCR3064 or 
a Lattice 1016.

Paul Burke

Hi,

the LPC915 has UART, 4 ADC channels and 2K FLASH.  It is much cheaper
than ATmega of the PIC16 proposed and does not even need an oscillator
(internal RC)

Schwob

Torbj&#4294967295;rn Heltne <torbjorn.heltne@amelektronikk.no> wrote in message news:<41a21a6b$1@news.broadpark.no>...
> Meindert Sprang wrote:
> 
> > Why not go for the ATmega162. It has two serial ports.
> 
> I can do without the TWI but need a couple of A/D channels.

"Schwob" <schwobus@aol.com> wrote in message
news:123e50e1.0411261615.6b4dfa5c@posting.google.com...
> Hi,
>
> the LPC915 has UART, 4 ADC channels and 2K FLASH.  It is much cheaper
> than ATmega of the PIC16 proposed and does not even need an oscillator
> (internal RC)

Mmmm... I am alway very sceptic about internal oscillators in combination
with UARTS. What do others think? Good/bad experiences?

Meindert